Automatic recirculation (ARC) valves are typically used in the oil and gas, power and chemical industries. In particular, ARC valves are used in connection with centrifugal pump applications to prevent pump overheating caused by the transfer of heat from a pump mechanism to the process fluid flowing through a system. During normal operation, this heat is transferred away from the pump and dissipated through the system via the process fluid. However, during periods of low process flow, the slower moving fluid does not dissipate the heat away from the pump sufficiently, thereby contributing to pump overheating. In addition, the vapor pressure increases as the temperature of the fluid within the pump increases, thereby increasing cavitation potential which damages the pump mechanism.
Recirculation valves are used to prevent this overheating by providing a path through which the pump maintains sufficient fluid flow during periods of low process flow through the system. Fluid enters a recirculation valve though a main inlet and exits the valve through a main outlet. The main valve element senses the rate of flow between the main inlet, and outlet. A pressure differential across the main valve element causes the valve to open to permit process flow to the main outlet. When the main valve is open, a recirculation or bypass portion of the valve is closed which prevents the flow of fluid to an associated recirculation outlet. During times of low downstream demand, the differential pressure across the main valve is insufficient to open the valve. When the main valve is closed, the recirculation or bypass valve is open which allows for the flow of fluid through the recirculation chamber and consequently to the recirculation outlet.
A drawback associated with the above referenced ARC valve is that the capacity through the bypass valve is fixed depending on the application. For example, the bypass valve may be configured to accommodate a particular bypass Cv. Unfortunately, when ARC valves are installed in the field, the Cv rating may or may not be ideal for actual process conditions. Thus, field changes must be done manually to accommodate for the design differentials. The above-referenced drawbacks and others are overcome by the present invention described herein with reference to the detailed description, drawings and appended claims.